numbers = [2, 3, 5, 7, 11, 13, 17]
contain5 = numbers.index(5) != nil
# contain5 is True
index5 = numbers.index(5)
# index5 is 2
contain10 = numbers.index(10) != nil
# contain10 is False
number2 = [1, 9, 8, 3, 1, 6, 71]
containNum = number2.count(1)
# containNum is 2
puts "contain5 is #{contain5}"
puts "index5 is #{index5}"
puts "contain10 is #{contain10}"
puts "containNum is #{containNum}"